MOT fail but concerned

richwhit

Hoping anyone can advise,
My daughter has an Astra 05 plate, 18,206 miles, no issues at all prior to MOT.
Drop the car in for its test. Same day receive call car failed MOT. Advised four new tyres required. Also failed on emissions
Return the phone call to garage. Disappointed to hear fail, told 1 of the tyres is a definite fail, the other 3 are on the limit and require replacing – no problem with that.
Emissions fail test also - Told that would be best to replace the Lambda sensors to see if that passes the emission test (cost circa £140). Not a guarantee that this will pass it through. If this does not pass then a new catalytic converter would be required (circa £160). Told that if all 4 tyres are replaced he would waive the 2nd emission test fee.
2 hours later – advised Lambda sensor had been replaced but reading still just under so new Cat would be required. I agreed that if it needed doing then so be it. I collect car from MOT station with a pass certificate. Cost £441 – breakdown as follows:-
Tyre, valve, wheel balance - £45
1 pre cat lamba (that’s how they spelt it) £60
1 post cat lamba - £65
1 eurecgm1082manifold catalytic converter £160
Friday – collect car. Drive home get approx 1 mile and engine cuts out once I take my foot off the accelerator. Return car to garage with same issues. Request the 2nd emission test result after the lambda sensors had been applied before the cat was required but told they could not print this out for me. 2 hours later receive call back from garage advising car is ready to collect. Return home all ok.
Saturday – drive approx 2 miles and car is cutting out as before - i.e; once you change down a gear and take foot of the accelerator the car ‘dies’ but does re-start. By pulling over and re-starting the car we just manage to get it back to the garage, manager not best pleased to see me and says he took the car for a good run on Friday, put some additive in ?, and he’s spent £10 petrol ‘out of my own my pocket after giving it a good run. Car currently at the garage as they have said they will look it on Monday.
Incidentally the emission test they have stapled to the MOT pass cert they have given me has no readings at all on it – result showing as ‘not checked’
Would appreciate any advices.
Thanks, Richard

arcon5

Don't know wh y they replaced p post cat lambda, it's nothing more than a check on the cats efficiency. Pre-cat only is used for engine management.
Doesn't sound like any real diagnostics took place, if it did they could have used lambda 1 and 2 data to help find the fault.
My thoughts are the cat didn't pass it either and the engines not running right but they didn't want to admit it.
I'd be interested to see if it failed emissions at idle or with revs on.

Fault could be related, could be completely unrelated. Idle control valve, tps, egr. Could be a million things we can't diagnose this online

tberry6686

Does anything odd happen when the car is just idling ? does it seem to hunt (rev up and down, stall) ? If so could be a sticking Idle control valve.

Dr._Shoe

My car failed on emissions with requiring a new cat- for the second year in a row! And I only do about 7,000 miles per year LOL!

Obviously it was "replaced" free of charge!

richwhit

Many thanks for the advices Arcon. Just to check then would there be any justifiable reason to replace the lambda sensor twice? If the first was one installed then replaced again within a couple of hours seems very expensive. Thanks in advance.

angrycrow

Often cars that fail on emisions had no need to fail.

A day or two before MOT take the car on a long high speed run I.e motorway.

Ensure you have a timeslot booked for your MOT and just before you drop it in take it for a good 30 minute run around local A roads to ensure the car is fully up to temp.

Then drop the car in for MOT and tell the tester you will wait whilst it is tested. Sit in the waiting room and watch them test it.

Emisions failure is often due to the engine not being up to temp.

If the garage know they are being watched you are likely to get a fair test.

Used this method for all my mot and only ever had one car fail on number plate lamp that blew during the test, new bulb fitted by me in test centre by me and pass certificate issued.

Despite there rep all my mots have been at quick fit and they have never tried it on with me, however I have seen them try it on with most of the other drivers who just dropped the car off.

On the other hand a different branch of KF did once fake a wheel alignment because they could not be bothered to undo the lock nut on the track rod end so I would never recommend them for any work being done.

To the OP, they have not replaced your lambda sensor twice, there are two in the exhaust, one before and one after the cat.

AdrianC

It's a ten year old car with very low mileage. It's probably never been fully up to temperature, so no wonder emissions are playing up.

arcon5

richwhit wrote: »

Many thanks for the advices Arcon. Just to check then would there be any justifiable reason to replace the lambda sensor twice? If the first was one installed then replaced again within a couple of hours seems very expensive. Thanks in advance.

There are 2 lambda sensors.
One is in the exhaust manifold, thus before to cat converter.
Second one is in the exhaust pipe, after the cat converter.
The first one detects the oxygen levels in the gasses to determine if the mixture is lean, rich or just right, the ECU then uses this data to decide whether to alter the fuel injection duration and timing.
The second one is merely a test as to whether the cat converter is working efficiently. If the data provided by Lambda 1 and Lambda 2 are the same then the cat isn't working, and visa versa.

So if you failed emissions, it could of course be down to a failed lambda, the pre-cat one though. Not post-cat sensor.

s_b

arcon gives good advice i can only add that to just put cats and lambdas on cars is a sure fire reason that fitting garage shouldn't be doing this kind of work but should be doing mot's only

worried_jim

18,000 miles in ten years. Needs an Italian tune up.

EdGasket

Sounds like they don't know what they are doing. My sister's car was taken to a place like that; kept failing on emissions. They tried pouring 'additive' in and thrashing it; to no avail. Tried to talk her into buying a new car. I suggested she took it to a reputable garage; they adjusted the carburettor (yes i do mean carb; no charge) and it passed.
You do need to have the engine hot when it is tested and take it to a decent garage who will check th eemissions properly. There is a general test and if it fails that, there is a make/model specific test. Did you get the emissions print out and check what they are failing against?